#include <stdio.h>
void main()
{
    int i,j,n=0,x;
    for(i=23;n==0;i+=2){
        for(j=1,x=i;j<=4 && x>=11;j++)
        if((x+1)%(j+1)==0)
        x-=(x+1)/(j+1);
        else{x=0;break;}
        if(j==5 && x==11)
        {
            printf("There are %d fishes at first.\n",i);
        }
    }
}